Campylopus contains nearly 200 species; in the Neotropics 65 species are presently recognized, of which about 50 are known from the tropical Andes. According to Frahm nearly 700 species were considered accepted species (legitimate names) prior to his revisionary studies; ca. 60 species and varieties previously described from the Andes are accepted as synonyms. The contributions by Frahm in Flora Neotropica (1991) and the previous treatment of the Andean Campylopus species (1978) are important references, as is the treatment for Central American by Allen (1994). In the tropical Andes Campylopus is found commonly in open to forested premontane to high montane, páramo and puna, less frequent in moist or dry lowlands, savannas and semi-dry deciduous foothill open forest; substrate includes soil, humus, logs, rocks, and epiphytic on shrubs and trees. Study Guide. A cross-section near mid leaf length is mandatory, furthermore, care must be given when removing leaves from the stem to do as little damage as possible to be able to determine the presents of alar cells that maybe hyaline or red, and if the basal cells (those immediately above the alar region) are thin- or thick-walled.